Golf club

ABSTRACT

The golf club of the present invention includes: a shaft; a golf club head having a hosel portion and a first opening portion that is formed on a side opposite to the hosel portion and is in communication with an interior space of the hosel portion, and having a hosel coupling portion in the interior space of the hosel portion; a first adapter having a first end portion and a second end portion, having a shaft receiving recessed portion that is open on the first end portion side and is fixed together with the shaft, and having a coupling portion in the second end portion; a second adapter accommodated in the interior space of the hosel portion, the second adapter having a first end portion and a second end portion; and a fixing member removably fixing the second adapter and the first adapter together.

TECHNICAL FIELD

The present invention relates to a golf club.

BACKGROUND ART

Various methods of coupling a golf club head and a shaft have been proposed in recent years. For example, Patent Literature 1 discloses a golf club in which two adapters are attached between the hosel portion of the golf club head and the shaft so as to make it possible to change the angle of attachment of the shaft to the golf club head. Specifically, it has the following configuration. First, a shaft adapter attached to the shaft is fixed so as to be inclined relative to the shaft. A head adapter attached to the hosel portion is removably attached to the head at one of multiple rotation positions. The shaft adapter is then fitted into the head adapter at an inclined angle relative thereto, and furthermore can be fitted therein at multiple rotation positions. Accordingly, the shaft can be attached to the golf club head at various angles by adjusting the rotation position of the head adapter relative to the hosel portion and the rotation position of the shaft adapter relative to the head adapter. This makes it possible to adjust the lie angle, loft angle, and face angle of the golf club to suit the user's preference.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2013-500059A

SUMMARY OF INVENTION

However, with the above-described golf club, the shaft adapter is accommodated in the interior space of the hosel portion, and therefore the rotation position at which the head adapter is attached to the hosel portion cannot be observed from the outside. For this reason, there is a problem in that the user therefore needs to detach and disassemble the two adapters in order to check the rotation position of the head adapter, and this task is troublesome.

The present invention has been achieved in order to solve the above problem, and an object thereof is to provide a golf club that enables the rotation position of an adapter to be observed without disassembling a coupling structure for coupling a shaft and a golf club head.

A golf club according to the present invention includes: a shaft; a golf club head having a hosel portion and a first opening portion that is formed on a side opposite to the hosel portion and is in communication with an interior space of the hosel portion, and having a hosel coupling portion in the interior space of the hosel portion; a first adapter having a first end portion and a second end portion, having a shaft receiving recessed portion that is open on the first end portion side and is fixed together with the shaft, and having a coupling portion in the second end portion; a second adapter accommodated in the interior space of the hosel portion, the second adapter having a first end portion and a second end portion, having a first coupling portion capable of being removably coupled to the coupling portion of the first adapter in the first end portion, and having a second coupling portion capable of being removably coupled to the hosel coupling portion inside the hosel portion; and a fixing member capable of being inserted into the interior space of the hosel portion via the first opening portion and accommodated therein, and removably fixing the second adapter and the first adapter together, wherein the shaft is configured so as to be coupled to the coupling portion of the first adapter in a state of being inclined relative thereto, the coupling portion of the first adapter is configured so as to be coupled to the second coupling portion of the second adapter in a state of being inclined relative thereto, the coupling portion of the first adapter and the first coupling portion of the second adapter can be coupled at a plurality of rotation positions, the second coupling portion of the second adapter and the hosel coupling portion of the hosel portion can be coupled at a plurality of rotation positions, and a second opening portion that is in communication with the interior space of the hosel portion and exposes at least a portion of an outer peripheral surface of the second adapter to the outside is formed in a surface of the golf club head.

Note that although the term “coupled” is used for the relationship between the adapters and the relationship between the adapter and the hosel portion in this description of the invention, the term “coupled” is intended to merely mean that at least two things are in contact so as to be immobile, and there are cases where it is not required that the two things do not separate even when external force is applied. Accordingly, besides the term “coupled”, the term “engaged” is also sometimes used to express this state.

In the above golf club, a position indicator indicating a rotation position may be provided on a portion of the second adapter that is exposed through the second opening portion.

The above golf club may be configured as follows. Specifically, the first adapter may have the first end portion and the second end portion at respective ends of a first axis, and be formed so as to be tube-shaped and extend along the first axis, and the shaft receiving recessed portion may extend along a second axis that intersects the first axis, the second adapter may have the first end portion and the second end portion at respective ends of a first axis, and be formed so as to be tube-shaped and extend along the first axis, and the first coupling portion may extend along a second axis that intersects the first axis, the coupling portion of the first adapter and the first coupling portion of the second adapter may be able to be coupled at a plurality of rotation positions about the second axis of the second adapter, and the second coupling portion of the second adapter and the hosel coupling portion of the hosel portion may be able to be coupled at a plurality of rotation positions about the first axis of the second adapter.

In the above golf clubs, the coupling portion of the first adapter may have a tube-shaped protruding portion, and the first coupling portion of the second adapter may have a recessed portion for receiving the coupling portion of the first adapter.

In the above case, a plurality of projections that extend in the first axis direction of the first adapter may be formed on a surface of the protruding portion of the coupling portion of the first adapter, and a plurality of grooves that extend in the second axis direction of the second adapter and are for receiving the plurality of projections may be formed in the recessed portion of the first coupling portion of the second adapter.

In the above golf clubs, the second coupling portion of the second adapter may be configured by an outer peripheral surface of the second adapter that is formed so as to be polygonal, and the hosel coupling portion may have a polygonal inner wall surface for receiving the second coupling portion.

The above golf clubs may further include a cover member that removably closes the first opening portion.

In the above golf clubs, a through-hole for insertion of a tool capable of operating the fastener may be formed in the cover member.

In the above golf clubs, a flange capable of coming into contact with a peripheral edge of an opening of the hosel portion may be formed in the first end portion of the first adapter, and a position indicator indicating a rotation position may be provided in the flange portion.

According to the golf club of the present invention, the second opening portion that is in communication with the interior space of the hosel portion and exposes at least a portion of the outer peripheral surface of the second adapter to the outside is formed in the surface of the golf club head, and therefore the rotation position of the second adapter can be observed through the second opening portion without disassembling the coupling structure for coupling the golf club head and the shaft. Accordingly, the user can check the lie angle, loft angle, and face angle of the golf club based on the current rotation angle of the second adapter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a golf club according to an embodiment of the present invention;

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is an exploded view of a coupling structure;

FIG. 4 is a front view of a golf club head with two adapters, a washer, and a fastener mounted therein, as viewed from the heel side;

FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4;

FIG. 6 is a bottom view of the golf club head in FIG. 4 from the sole portion side;

FIG. 7A is a side view of a first adapter, and FIG. 7B is a cross-sectional view of the same;

FIG. 8A is a perspective view of a second adapter from above, FIG. 8B is a cross-sectional view of the same, and FIG. 8C is a perspective view of the same from below;

FIG. 9A is a perspective view of another example of the second adapter, and FIG. 9B is a cross-sectional view of the same;

FIG. 10A is a perspective view of yet another example of the second adapter, and FIG. 10B is a cross-sectional view of the same;

FIG. 11 is a cross-sectional view of an example of a golf club head with the second adapter shown in FIGS. 10A and 10B mounted therein;

FIG. 12A is a front view of a golf club head having a cap mounted thereon, and FIG. 12B is a cross-sectional view of the same;

FIG. 13 is a cross-sectional view of another example of the golf club head;

FIG. 14A is a front view of a neck member, and FIG. 14B is a cross-sectional view of the same; and

FIG. 15 is a side view of another example of the first adapter.

REFERENCE SIGNS LIST

-   -   10 Golf club head     -   20 Shaft     -   31 Lower opening (first opening portion)     -   5 Hosel portion     -   55 Window (second opening portion)     -   6 First adapter     -   7 Second adapter     -   8 Washer (fixing member)     -   9 Fastener (fixing member)

DESCRIPTION OF EMBODIMENTS

An embodiment of a golf club according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a golf club head according to the present embodiment, and FIG. 2 is a plan view of FIG. 1. Note that the reference state of the golf club head will be described later. Although the following description uses the orientation shown in the drawings as a reference, this is for the sake of convenience in the description, and this orientation is not intended to limit the invention. Also, the axial direction in the following description is generally the direction in which the shaft extends unless otherwise stated, and is not intended to have a strict definition.

1. Overall Structure of Golf Club

As shown in FIGS. 1 and 2, the golf club of the present embodiment includes a shaft 20 and a golf club head 10 (sometimes referred to hereinafter as simply the “head”) coupled to an end portion of the shaft 20. Also, the shaft 20 and the golf club head 10 are coupled together by a later-described coupling structure, and are configured such that it is possible to change the axial rotation position of the shaft 20 relative to the head 10. These members will be described in detail below.

The shaft 20 is shaped as a hollow tube, has a lower end portion to which the above-mentioned golf club head 10 is coupled, and has an upper end portion to which a grip (not shown) is fixed.

The golf club head 10 is a hollow structure and has wall surfaces formed by a face portion 1, a crown portion 2, a sole portion 3, a side portion 4, and a hosel portion 5. The face portion 1 has a face surface, which is the surface for hitting a ball, and the crown portion 2 is adjacent to the face portion 1 and constitutes the upper surface of the head. The sole portion 3 constitutes the bottom surface of the head 10, and is adjacent to the face portion 1 and the side portion 4. Also, the side portion 4 is the portion between the crown portion 2 and the sole portion 3, and extends from the toe side of the face portion 1, across the back side of the head 10, to the heel side of the face portion 1. Furthermore, the hosel portion 5 is a cylindrical portion provided adjacent to the heel side of the crown portion 2, and has an attachment hole 51 for the insertion of a later-described first adapter 6. Note that although the head 10 described here is a wood head such as a driver (#1) or fairway wood head, it is not limited to being a wood head, and may be a so-called utility head, hybrid head, or the like.

2. Coupling Structure for Coupling Shaft and Golf Club Head

Next, a coupling structure for coupling the shaft 20 and the golf club head 10 will be described. FIG. 3 is an exploded view of the coupling structure. As shown in this figure, in this coupling structure, the shaft 20 and the golf club head 10 are coupled via the first adapter 6 and a second adapter 7, and these two adapters 6 and 7 are fixed inside the golf club head 10 by a washer 8 and a fastener 9. This coupling structure will be described in detail below.

2.1 Coupling-Related Structure of Golf Club Head

First, the structure of the golf club head 10 will be described with reference to FIGS. 4 to 6 as well. FIG. 4 is a front view of the golf club head with the two adapters, the washer, and the fastener mounted therein, as viewed from the heel side, FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4, and FIG. 6 is a bottom view of the golf club head in FIG. 4 from the sole portion side.

As shown in FIGS. 4 to 6, the interior space of the hosel portion 5 extends to the side portion 4 side and the sole portion 3 side in a direction generally parallel to the axial direction of the shaft 20. A recessed portion 31 is formed in a portion of the sole portion 3 on the side opposite to the hosel portion 5. This recessed portion 31 is constituted by an arc-shaped side surface 311 that extends substantially parallel to the interior space, and a base surface 312 that extends generally perpendicularly from the side face 311. Also, a lower opening 313 in communication with the interior space is formed in the base face 312. A rectangular window 55 in communication with the interior space is also formed on the attachment hole 51 side relative to the base face 312. This window 55 is formed by cutting out a portion of the base face 312 and the side portion 4 so as to expose a portion of the interior space (a large-diameter portion 502 that will be described later) to the outside. When the later-described second adapter 7 is arranged in the interior space, a portion of the second adapter 7 is exposed through the window 55.

The interior space of the hosel portion 5 is defined by a cylindrical small-diameter portion 501 and the quadrangular prism-shaped large-diameter portion 502 that is continuous with the small-diameter portion 501 and is in communication with the lower opening 313. The small-diameter portion 501 is formed so as to be tapered such that its diameter slightly increases as it extends toward the large-diameter portion 502. Also, the lower opening of the large-diameter portion 502 is fixed so as to coincide with the lower opening 313. During assembly, the first adapter 6 is inserted into the small-diameter portion 501 from the attachment hole 51 side, and the second adapter 7 is inserted into the large-diameter portion 502 from the lower opening 313 side. The two adapters 6 and 7 are then removably coupled together in the interior space, and are detachably fixed by the washer 8 and the threaded fastener 9. As shown in FIG. 3, the fastener 9 is formed by a head portion 91 and a threaded portion 92 coupled thereto, and a rectangular recessed portion 911 (see FIGS. 5 and 6) for the insertion of a wrench is formed in the head portion 91. Note that in the interior space of the hosel portion 5, a step formed at the connection between the small-diameter portion 501 and the large-diameter portion 502 is coupled to a coupling portion 72 of the later-described second adapter 7, and this portion corresponds to a hosel coupling portion of the present invention. The term “coupled” here need only mean that at least two things are in contact so as to be immobile, and it is not required that the two things do not separate even when external force is applied.

2.2 First Adapter

Next, the first adapter 6 will be described with reference to FIGS. 7A and 7B. FIG. 7A is a side view of the first adapter, and FIG. 7B is a cross-sectional view of the same. As shown in these figures, the first adapter 6 includes a tube-shaped body portion 61 and a tube-shaped coupling portion 62 that is attached to the lower end portion of the body portion 61 and has a smaller diameter than the body portion 61. These portions are formed integrally with each other. The body portion 61 has a first axis X1 as its axial center, is externally shaped so as to extend along the first axis X1 in the shape of a cylinder, and has a shaft receiving recessed portion 611 that is open on the upper end side. This shaft receiving recessed portion 611 has a cylindrical inner wall surface that extends along a second axis X2 that intersects the first axis X1 at an angle of approximately 1 degree, and the lower end portion of the shaft 20 is inserted into this shaft receiving recessed portion 611. The shaft 20 is fixed to the shaft receiving recessed portion 611 by adhesion or the like. Accordingly, the shaft 20 is fixed such that an axial center S (see FIG. 1) thereof extends along the second axis X2 of the first adapter 6 and extends from the first adapter 6 at an inclined angle.

Also, although the outer diameter of the body portion 61 of the first adapter 6 is smaller than the attachment hole 51 of the hosel portion 5, a flange portion 612 that extends outward in the diameter direction is formed on the outer peripheral surface of the body portion 61, and this flange portion 612 comes in contact with the peripheral edge of the attachment hole 51 of the hosel portion 5. Accordingly, the flange portion 612 of the first adapter 6 is arranged outside the attachment hole 51, and the portion of the first adapter 6 below the flange portion 612 is arranged inside the small-diameter portion 501 of the interior space in the hosel portion 5. Also, by, for example, providing multiple rotation position indicators 65 on the outer peripheral surface of the flange portion 612 as shown in the example in FIG. 3, an angle can be set according to the user's preference, as will be described later, by aligning one of the rotation position indicators with a reference indicator 52 provided on the peripheral edge of the opening of the attachment hole 51 in the hosel portion 5.

The coupling portion 62 of the first adapter 6 is formed as a tube that extends along the first axis X1, and also has a threaded hole 621 that is open downward. Female threading is formed in this threaded hole 621. Also, multiple projections 622 that extend along the first axis X1 are formed on the outer peripheral surface of the coupling portion 62 at predetermined intervals in the circumferential direction. Note that the upper end portion of the first adapter 6 in FIG. 7 corresponds to a first end portion of the present invention, and the lower end portion of the first adapter 6 corresponds to a second end portion of the present invention.

2.3 Second Adapter

Next, the second adapter 7 will be described with reference to FIGS. 8A to 8C. FIG. 8A is a perspective view of the second adapter from above, FIG. 8B is a cross-sectional view of the same, and FIG. 8C is a perspective view of the same from below. As shown in these figures, the second adapter 7 includes a cylindrical body portion (first coupling portion) 71 and a quadrangular prism-shaped coupling portion (second coupling portion) 72 that is integrally coupled to the lower end of the body portion 71 and has a larger diameter than the body portion 71. The body portion 71 has a first axis Y1 as its axial center, is externally shaped so as to extend along the first axis Y1 in the shape of a cylinder, and has a recessed portion 711 that is open on the upper end side. This recessed portion 711 has a cylindrical inner wall surface that extends along a second axis Y2 that intersects the first axis Y1 at an angle of approximately 1 degree, and the coupling portion 62 of the first adapter 6 is removably inserted into this recessed portion 711. In order to receive the coupling portion 62, multiple grooves 712 for engagement with the projections 622 of the coupling portion 62 are formed so as to extend along the second axis Y2 on the inner wall surface of the recessed portion 711. According to this configuration, when attached to the recessed portion 711, the first adapter 6 extends along the second axis Y2 of the second adapter 7, and therefore is fixed so as to extend from the second adapter 7 at an inclined angle. Also, since the coupling portion 62 and the recessed portion 711 are splined together, the two adapters 6 and 7 are coupled so as to be incapable of axial rotation. At this time, the number of rotation positions at which the two adapters 6 and 7 can be coupled is equal to the number of projections 622. Note that the number of projections 622 and grooves 712 is 2 to 12, for example, but there is no particular limitation on the number thereof. Also, in this configuration, the second axis X2 of the first adapter 6 and the second axis Y2 of the second adapter 7 intersect each other, rather than being parallel, when the two adapters 6 and 7 are coupled.

The body portion 71 of the second adapter 7 is arranged so as to be coupled to the first adapter 6 in the small-diameter portion 501 of the interior space in the hosel portion 5. On the other hand, the coupling portion 72 of the second adapter 7 is arranged in the large-diameter portion 502 of the interior space. In other words, the quadrangular prism-shaped outer peripheral surface of the coupling portion 72 engages with the quadrangular prism-shaped inner wall surface of the large-diameter portion 502. Accordingly, the second adapter 7 is arranged so as to be incapable of axial rotation relative to the interior space of the hosel portion 5. Since the coupling portion 72 of the second adapter 7 is quadrangular prism-shaped, it can be fitted into the large-diameter portion 502 of the interior space at any of four rotation positions. Also, a rotation position indicator 722 is provided on the side surface and the lower end surface of the coupling portion 72, and the position of this indicator is exposed through the lower opening 313 and can be observed through the recessed portion. Furthermore, a portion of the outer wall surface of the coupling portion 72 can be observed through the previously-mentioned window 55.

Also, a through-hole is formed between the coupling portion 72 and the body portion 71. This through-hole is defined by a circular large-diameter portion 731 that is open on the coupling portion 72 side and a circular small-diameter portion 732 that is continuous with and has a smaller diameter than the large-diameter portion 731, and is also in communication with the recessed portion 711. The previously-mentioned circular washer 8 is arranged in the large-diameter portion 731, and the fastener 9 is arranged therein along with the washer 8. The fastener 9 presses the washer 8 with the head portion 91, and the threaded portion 92 passes through the small-diameter portion 732 and extends to the interior of the recessed portion 711. The threaded portion 92 is then screwed to the coupling portion 62 of the first adapter 6, which has been inserted into the recessed portion 711. The large-diameter portion 731 is formed such that the surface on which the washer 8 is arranged is orthogonal to the second axis Y2. That is to say, since the first adapter 6 extends along the second axis Y2 when it is coupled to the second adapter 7, the washer 8 and the fastener 9 firmly fix them together along the direction in which the first adapter 6 extends. Note that the upper end portion of the second adapter 7 in FIG. 8B corresponds to the first end portion of the present invention, and the lower end portion of the second adapter 7 corresponds to the second end portion of the present invention.

Note that the adapters 6 and 7 used in the coupling structure can be formed from various types of materials such as Ti (6-4Ti) or Al (Al7075).

3. Assembly of Shaft and Golf Club Head

Next, a method of assembling the golf club having the above configuration will be described. First, the second adapter 7 is inserted into the lower opening 313 on the sole portion 3 side. At this time, the rotation position of the coupling portion 72 of the second adapter 7 is appropriately determined, and the coupling portion 72 is fitted into the large-diameter portion 502 of the interior space at a desired rotation position. Next, the first adapter 6 having the shaft 20 fixed thereto is inserted into the attachment hole 51 of the hosel portion 5 with the coupling portion 62 facing downward. At this time, one of the rotation position indicators 65 on the flange portion 612 of the first adapter 6 is aligned with the reference indicator 52 on the peripheral edge of the attachment hole 51. The coupling portion 62 of the first adapter 6 is thus inserted into the small-diameter portion 501 of the interior space and splined to the body portion 71 of the second adapter 7. Next, the washer 8 is arranged in the large-diameter portion 731 of the coupling portion 72 of the second adapter 7, and the threaded portion 92 of the fastener 9 is inserted into the small-diameter portion 732 and screwed to the coupling portion 62 of the first adapter 6. The second adapter 7 is thus fastened and fixed to the first adapter 6.

When the shaft 20 and the head 10 have been fixed as described above, the shaft 20 is fixed to the first adapter 6 so as to be inclined at an angle of 1 degree relative thereto. Also, the first adapter 6 is fixed to the second adapter 7 so as to be inclined at an angle of 1 degree relative thereto. Accordingly, the shaft 20 is fixed so as to be inclined at a maximum of 2 degrees relative to the second adapter 7. In this way, the first adapter 6 is fixed so as to be inclined relative to the second adapter 7 at one of the rotation positions, and since the small-diameter portion 501 of the interior space housing the first adapter 6 is tapered, the first adapter 6 does not interfere with the inner wall surface of the small-diameter portion 501 regardless of the rotation position at which the first adapter 6 is fixed to the second adapter 7.

Here, if the rotation position of the first adapter 6 relative to the second adapter 7 is changed while maintaining the rotation position of the second adapter 7, the angle of attachment of the shaft 20 to the head 10 is changed, thus making it possible to change the lie angle, loft angle, and face angle. Also, the lie angle, loft angle, and face angle can be changed more finely by changing the rotation angle of the second adapter 7 relative to the large-diameter portion 502. For example, if there are 12 rotation angles of the first adapter 6 relative to the second adapter 7 and four rotation angles of the second adapter 7 relative to the large-diameter portion 502, it is possible to make a change to a total of 48 combinations of a lie angle, a loft angle, and a face angle.

In this case, rotation position indicators are provided on the flange portion 612 of the first adapter 6 and are exposed to the outside, and therefore the user can easily observe the rotation position of the first adapter 6. Also, since a portion of the large-diameter portion 502 of the interior space in the hosel portion 5 is exposed to the outside through the window 55, a portion of the outer peripheral surface of the coupling portion 72 of the second adapter 7 arranged in the large-diameter portion 501 can be observed through the window 55. This enables the user to check the rotation position indicator 722 and to observe the rotation position of the second adapter 7. Accordingly, the user can check the rotation position of the first adapter 6 and the rotation position of the second adapter 7 without disassembling the coupling structure, and thus can check the lie angle, loft angle, and face angle of the golf club.

4. Variations

Although an embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the invention. The following are examples of modifications that can be made.

4.1

In the above embodiment, the second adapter 7 is fixed to the large-diameter portion 502 of the interior space in the hosel portion 5 using the coupling portion 72 of the second adapter 7 that is formed so as to be rectangular. In other words, it is fixed so as to be incapable of rotation relative to the large-diameter portion 502, but there are no particular limitations on the method of fixing the second adapter 7 so as to be incapable of rotation relative to the interior space, and various aspects are possible. For example, in FIGS. 9A and 9B, the second adapter 7 is constituted by a cylindrical body portion 71 and a coupling portion 72 whose diameter is larger than the body portion 71. The coupling portion 72 is cylindrical, and the large-diameter portion 502 of the interior space in the hosel portion 5 is correspondingly formed so as to be cylindrical. Also, four protruding portions 721 are formed on the upper surface of the coupling portion 72 of the second adapter 7, and fixing holes for receiving the four protruding portions 721 are formed in the large-diameter portion 502 of the interior space. According to this configuration, the second adapter 7 is fixed so as to be incapable of rotation in the interior space, and can be fixed at any of four rotation positions. Note that there are no particular limitations on the number of protruding portions 721 and fixing holes, and any number of them may be provided. Also, the protruding portions may be formed in the interior space, and the fixing holes may be formed in the second adapter 7.

4.2

Alternatively, in FIGS. 10A and 10B, the second adapter 7 is formed so as to be quadrangular prism-shaped. Specifically, instead of combining portions having different outer diameters, it is a member having a constant outer diameter. With the exception of having a constant outer diameter, this second adapter 7 is the same as the second adapter 7 described in the above embodiment. In other words, instead of separately providing the coupling portion, the outer peripheral surface of the entire second adapter 7 is formed so as to be rectangular, and this outer peripheral surface constitutes the coupling portion. A rectangular inner wall surface 503 having a constant diameter is correspondingly formed in the interior space of the hosel portion 5 as shown in FIG. 11. Note that in order to prevent the two adapters 6 and 7 from coming out of the interior space, it is possible to provide the inner wall surface 503 with a flange 504 that extends inward in the diameter direction, and engage this flange 504 with a step between the body portion 61 and the coupling portion 62 of the first adapter 6.

4.3

Also, although the two adapters 6 and 7 are splined together in the above embodiment, the present invention is not limited to this. In other words, as long as the two adapters 6 and 7 can be fixed at multiple axial rotation positions, and furthermore the two adapters 6 and 7 are coupled so as to be incapable of rotation, there are no particular limitations on the aspects of this. For example, a configuration is possible in which the coupling portion 61 of the first adapter 6 is formed so as to be polygonal, and the recessed portion 711 of the second adapter 7 has a polygonal inner wall surface for receiving the coupling portion 61.

4.4

Also, in the above embodiment, the coupling portion 62 of the first adapter 6 is formed as a cylindrical protruding portion, and the recessed portion 711 for receiving the coupling portion 62 is formed in the second adapter 7, but the coupling structure for coupling the two adapters is not limited to this. For example, it is possible to form a tube-shaped protruding portion on the upper end portion of the second adapter 7, and form a recessed portion for receiving the protruding portion on the lower end portion of the first adapter 6.

4.5

In the above embodiment, the shaft 20 is inclined at an angle of 1 degree relative to the first adapter 6, and the first adapter 6 is inclined at an angle of 1 degree relative to the second adapter 7, but there are no particular limitations on these angles. Also, the two angles may be different.

4.6

Although the lower opening 313 in communication with the interior space is exposed via the recessed portion 31 formed in the surface of the golf club head 10 in the above embodiment, a cap for blocking the recessed portion 31 may be provided. For example, in FIGS. 12A and 12B, a cap 85 is formed by a side wall surface 851 that extends along the side surface 311 of the recessed portion 31, an outer wall surface 852 that extends along the outer peripheral surface of the golf club head 10, and an end surface 853 that opposes the base surface 312 of the recessed portion 31. The length of the side wall surface 851 in the axial direction is shorter than that of the side surface 311 of the recessed portion 31, and thus a gap is formed between the base surface 312 of the recessed portion 31 and the end surface 853. Also, a through-hole 854 that extends in the axial direction is formed between the outer wall surface 852 and the end surface 853, and a tool such as a wrench can be inserted through this through-hole 54 from outside the cap 85. It is then possible to engage the tool with the head portion 91 of the fastener 9 and detach the fastener 9 while the cap 85 is closed. According to this configuration, the recessed portion 31 is blocked by the cap 85, thus making it possible to improve the designability of the head 10 and prevent loss of the fastener 9 when it is detached. Note that since a gap exists between the cap 85 and the base surface 312, the rotation position of the second adapter 7 can be changed by inserting a finger through the gap, for example. Accordingly, even if the cap 85 is attached, the rotation position of the second adapter 7 can be checked through not only the gap, but also through the window 55 formed in the surface of the head 10.

4.7

There are no particular limitations on the shape of the window 55, and as long as a cutout is formed in the inner wall surface of the interior space in the hosel portion 5 and the outer peripheral surface of the second adapter 7 can be checked, there are no particular limitations on the width, the axial length, the shape, and the like of the window. Also, the window 55 is not necessarily required to be in communication with the lower opening 313 and the recessed portion 31, and it is possible for them to be separated. In other words, the window 55 may be formed separately from the recessed portion 31 and the lower opening 313, and may be formed as an independent window in the surface of the head 10. Also, the window 55 can be made even larger so as to expose not only the second adapter 7 but also the position of coupling with the first adapter 6 to the outside. If a rotation position indicator is provided in the vicinity of the position at which the first adapter 6 is coupled to the second adapter 7, it is possible to observe the relationship between the rotation positions of the two adapters 6 and 7. Note that there is no particular distinction between the rotation position indicator and the reference indicator, and there are no particular limitations on them as long as rotation position alignment can be performed. In other words, it is sufficient that some sort of indicator is provided, and it is possible to provide the reference indicator on the first adapter 6 and provide the rotation position indicator on the peripheral edge of the attachment hole 51.

4.8

Also, although the rotation position indicator 722 on the second adapter 7 is provided by a line, it can alternatively be provided by a graphic, a number, or the like, and it is alternatively possible to process a portion of the second adapter 7, such as cutting out a portion or providing a protruding portion.

4.9

Although a portion of the head forms the interior space in the hosel portion in the above embodiment, the hosel portion 5 may be constituted by attaching a tube-shaped neck member 50 to the golf club head as shown in FIG. 13, for example. For example, an attachment through-hole 21 that extends substantially parallel to the axial direction of the shaft is formed at a position in the golf club head 10 where the hosel portion 5 is to be formed (a position on the heel side of the crown portion 2). This attachment through-hole 21 extends toward the sole portion 3 side. Also, the above-described recessed portion 31 is formed in a portion of the sole portion 3 on the side opposite to the hosel portion 5.

The neck member 50 is fixed in the thus-formed attachment through-hole 21 as shown in FIGS. 14A and 14B. The neck member 50 is constituted by a cylindrical small-diameter portion 501 and a quadrangular prism-shaped large-diameter portion 502 that is continuous with the small-diameter portion 501 and is in communication with the lower opening 312. The small-diameter portion 501 is formed so as to be tapered such that its diameter slightly increases as it extends toward the large-diameter portion 502. Also, the flange portion 503 is formed on the outer peripheral surface of the small-diameter portion 501, and this flange portion 503 engages with the peripheral edge of the opening of the attachment through-hole 21 on the crown portion 2 side. The portion of the small-diameter portion 501 below the flange portion 503 is then inserted into the attachment through-hole 21, and the opening on the lower side of the large-diameter portion 502 is fixed so as to coincide with the lower opening 313. In this way, the interior space of the hosel portion 5 is formed by the neck member 50, and the opening on the small-diameter portion 501 side constitutes the attachment hole 51 of the hosel portion 5.

4.10

In the above embodiment, the outer peripheral surface of the first adapter 6 is formed so as to extend parallel to the first axis X1, and the shaft receiving recessed portion 611 is formed so as to extend along the second axis X2 that intersects the first axis X1, but the first adapter 6 can be formed as shown in FIG. 15, for example. As shown in this figure, in this example, the body portion 61 of the first adapter 6 is inclined relative to the coupling portion 62. Specifically, the coupling portion 62 is formed so as to extend along the first axis X1, and the outer peripheral surface of the body portion 61 is formed so as to extend along the second axis X2. Also, the shaft receiving recessed portion 611 formed in the body portion 61 is also formed so as to extend along the second axis X2. According to this configuration as well, the axial center S of the shaft 20 extends along the second axis X2, and therefore the shaft 20 can be fixed so as to be inclined relative to the first adapter 6. Accordingly, the coupling portion 62 of the first adapter 6 is configured so as to be coupled to the coupling portion 72 of the second adapter 7 in a state of being inclined relative thereto. Note that in order for the entirety of the flange portion 612 to come into contact with the attachment hole 51 of the hosel portion 5, the flange portion 612 is formed so as to be inclined relative to the body portion 61.

4.11

Note that since the golf club head configured as described above is a hollow structure, it can be manufactured by joining two or more members together. Specifically, it can be manufactured by joining together a head body provided with one or two or more openings in communication with a hollow portion, and a separate member that blocks these openings. For example, it is possible to constitute the head by constituting only the crown portion 2 and the face portion 1 as separate members and combining them with the head body, or forming the head body such that an opening is provided in the sole portion 3 and the side portion 4 and blocking this opening with a separate member. Also, this head body can be manufactured by casting using a known lost-wax precision casting method, for example. 

1. A golf club comprising: a shaft; a golf club head having a hosel portion and a first opening portion that is formed on a side opposite to the hosel portion and is in communication with an interior space of the hosel portion, and having a hosel coupling portion in the interior space of the hosel portion; a first adapter having a first end portion and a second end portion, having a shaft receiving recessed portion that is open on the first end portion side and is fixed together with the shaft, and having a coupling portion in the second end portion; a second adapter accommodated in the interior space of the hosel portion, the second adapter having a first end portion and a second end portion, having a first coupling portion capable of being removably coupled to the coupling portion of the first adapter in the first end portion, and having a second coupling portion capable of being removably coupled to the hosel coupling portion inside the hosel portion; and a fixing member capable of being inserted into the interior space of the hosel portion via the first opening portion and accommodated therein, and removably fixing the second adapter and the first adapter together, wherein the shaft is configured so as to be coupled to the coupling portion of the first adapter in a state of being inclined relative thereto, the coupling portion of the first adapter is configured so as to be coupled to the second coupling portion of the second adapter in a state of being inclined relative thereto, the coupling portion of the first adapter and the first coupling portion of the second adapter can be coupled at a plurality of rotation positions, the second coupling portion of the second adapter and the hosel coupling portion of the hosel portion can be coupled at a plurality of rotation positions, and a second opening portion that is in communication with the interior space of the hosel portion and exposes at least a portion of an outer peripheral surface of the second adapter to the outside is formed in a surface of the golf club head.
 2. The golf club according to claim 1, wherein a position indicator indicating a rotation position is provided on a portion of the second adapter that is exposed through the second opening portion.
 3. The golf club according to claim 1, wherein the first adapter has the first end portion and the second end portion at respective ends of a first axis, and is formed so as to be tube-shaped and extend along the first axis, and the shaft receiving recessed portion extends along a second axis that intersects the first axis, the second adapter has the first end portion and the second end portion at respective ends of a first axis, and is formed so as to be tube-shaped and extend along the first axis, and the first coupling portion extends along a second axis that intersects the first axis, the coupling portion of the first adapter and the first coupling portion of the second adapter can be coupled at a plurality of rotation positions about the second axis of the second adapter, and the second coupling portion of the second adapter and the hosel coupling portion of the hosel portion can be coupled at a plurality of rotation positions about the first axis of the second adapter.
 4. The golf club according to claim 3, wherein the coupling portion of the first adapter has a tube-shaped protruding portion, and the first coupling portion of the second adapter has a recessed portion for receiving the coupling portion of the first adapter.
 5. The golf club according to claim 4, wherein a plurality of projections that extend in the first axis direction of the first adapter are formed on a surface of the protruding portion of the coupling portion of the first adapter, and a plurality of grooves that extend in the second axis direction of the second adapter and are for receiving the plurality of projections are formed in the recessed portion of the first coupling portion of the second adapter.
 6. The golf club according to claims 1, wherein the second coupling portion of the second adapter is configured by an outer peripheral surface of the second adapter that is formed so as to be polygonal, and the hosel coupling portion has a polygonal inner wall surface for receiving the second coupling portion.
 7. The golf club according to claim 1, further comprising a cover member that removably closes the first opening portion.
 8. The golf club according to claim 7, wherein a through-hole for insertion of a tool capable of operating the fastener is formed in the cover member.
 9. The golf club according to claim 1, wherein a flange capable of coming into contact with a peripheral edge of an opening of the hosel portion is formed in the first end portion of the first adapter, and a position indicator indicating a rotation position is provided in the flange portion.
 10. The golf club according to claim 1, wherein the interior space of the hosel portion is defined by a small-diameter portion and a large-diameter portion that is continuous with the small-diameter portion and is in communication with the first opening portion, and the small-diameter portion is formed so as to be tapered such that the diameter increases as the small-diameter portion extends toward the large-diameter portion. 